Zooplankton of Alakol lake (Southeastern Kazakhstan) and its interannual variability

Abstract

 This work aims to analyze the interannual variability of zooplankton in Lake Alakol during different periods  of the hydrological cycle based on our own (2002, 2004–2007) and literature data. In zooplankton  composition, 132 taxa were recorded, from 15 to 64 taxa over the years. The average long-term abundance of  zooplankton was 172.5±58.2 thousand specimens/m3 , with a biomass of 0.9±0.2 g/m3 . In the long-term  aspect, zooplankton abundance changed 36 times and the biomass 10 times. A tendency has been revealed for  the quantitative variables of zooplankton to increase in high-water years (1954–1968, 1996–1997, 2005) and  to decrease during low-water periods (1983, 2000, 2002, 2004, 2006, 2007). During all research periods,  rotifers dominated, with a more minor role of crustaceans. The dominant species complex included rotifers  Brachinus plicatilis, Brachinus quadridentatus, Keratella quadrata, crustaceans Arctodiaptomus salinus,  Mesocyclops leuckarti. The relative stability of the composition of background species of planktonic  invertebrates for more than half a century is due to their broad ecological plasticity.